Fix crash when CanvasBox draws with nil canvas

go.mod

@@ -3,11 +3,8 @@ module git.tebibyte.media/tomo/backend
 go 1.20
 
 require (
-	git.tebibyte.media/tomo/tomo v0.34.0
+	git.tebibyte.media/tomo/tomo v0.38.0
 	git.tebibyte.media/tomo/typeset v0.7.1
-)
-
-require (
 	git.tebibyte.media/tomo/xgbkb v1.0.1
 	github.com/jezek/xgb v1.1.1
 	github.com/jezek/xgbutil v0.0.0-20231116234834-47f30c120111

go.sum

@@ -1,6 +1,6 @@
 git.tebibyte.media/sashakoshka/xgbkb v1.0.0/go.mod h1:pNcE6TRO93vHd6q42SdwLSTTj25L0Yzggz7yLe0JV6Q=
-git.tebibyte.media/tomo/tomo v0.34.0 h1:r5yJPks9rtzdDI2RyAUdqa1qb6BebG0QFe2cTmcFi+0=
-git.tebibyte.media/tomo/tomo v0.34.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
+git.tebibyte.media/tomo/tomo v0.38.0 h1:K5TP67RxnszudeNfmGZiU5cFTRjFueXiI3NCsgw+05U=
+git.tebibyte.media/tomo/tomo v0.38.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
 git.tebibyte.media/tomo/typeset v0.7.1 h1:aZrsHwCG5ZB4f5CruRFsxLv5ezJUCFUFsQJJso2sXQ8=
 git.tebibyte.media/tomo/typeset v0.7.1/go.mod h1:PwDpSdBF3l/EzoIsa2ME7QffVVajnTHZN6l3MHEGe1g=
 git.tebibyte.media/tomo/xgbkb v1.0.1 h1:b3HDUopjdQp1MZrb5Vpil4bOtk3NnNXtfQW27Blw2kE=

internal/system/box.go

@@ -19,6 +19,11 @@ type box struct {
 	parent parent
 	outer  anyBox
 
+	role           tomo.Role
+	styleCookie    event.Cookie
+	lastStyleNonce int
+	lastIconsNonce int
+
 	bounds              image.Rectangle
 	minSize             image.Point
 	userMinSize         image.Point
@@ -42,19 +47,21 @@ type box struct {
 	drawer canvas.Drawer
 
 	on struct {
-		focusEnter event.FuncBroadcaster
-		focusLeave event.FuncBroadcaster
-		dndEnter   event.FuncBroadcaster
-		dndLeave   event.FuncBroadcaster
-		dndDrop    event.Broadcaster[func (data.Data)]
-		mouseEnter event.FuncBroadcaster
-		mouseLeave event.FuncBroadcaster
-		mouseMove  event.FuncBroadcaster
-		mouseDown  event.Broadcaster[func (input.Button)]
-		mouseUp    event.Broadcaster[func (input.Button)]
-		scroll     event.Broadcaster[func (float64, float64)]
-		keyDown    event.Broadcaster[func (input.Key, bool)]
-		keyUp      event.Broadcaster[func (input.Key, bool)]
+		focusEnter  event.FuncBroadcaster
+		focusLeave  event.FuncBroadcaster
+		dndEnter    event.FuncBroadcaster
+		dndLeave    event.FuncBroadcaster
+		dndDrop     event.Broadcaster[func (data.Data)]
+		mouseEnter  event.FuncBroadcaster
+		mouseLeave  event.FuncBroadcaster
+		mouseMove   event.FuncBroadcaster
+		mouseDown   event.Broadcaster[func (input.Button)]
+		mouseUp     event.Broadcaster[func (input.Button)]
+		scroll      event.Broadcaster[func (float64, float64)]
+		keyDown     event.Broadcaster[func (input.Key, bool)]
+		keyUp       event.Broadcaster[func (input.Key, bool)]
+		styleChange event.FuncBroadcaster
+		iconsChange event.FuncBroadcaster
 	}
 }
 
@@ -106,6 +113,10 @@ func (this *box) MinimumSize () image.Point {
 	return this.minSize
 }
 
+func (this *box) Role () tomo.Role {
+	return this.role
+}
+
 func (this *box) borderSum () tomo.Inset {
 	sum := tomo.Inset { }
 	for _, border := range this.border {
@@ -117,6 +128,15 @@ func (this *box) borderSum () tomo.Inset {
 	return sum
 }
 
+func (this *box) borderAndPaddingSum () tomo.Inset {
+	sum := this.borderSum()
+	sum[0] += this.padding[0]
+	sum[1] += this.padding[1]
+	sum[2] += this.padding[2]
+	sum[3] += this.padding[3]
+	return sum
+}
+
 func (this *box) SetBounds (bounds image.Rectangle) {
 	if this.bounds == bounds { return }
 	this.bounds = bounds
@@ -182,6 +202,13 @@ func (this *box) SetPadding (padding tomo.Inset) {
 	this.invalidateMinimum()
 }
 
+func (this *box) SetRole (role tomo.Role) {
+	if this.role == role { return }
+	this.role = role
+	this.lastStyleNonce = -1
+	this.outer.recursiveReApply()
+}
+
 func (this *box) SetDNDData (dat data.Data) {
 	this.dndData = dat
 }
@@ -272,6 +299,12 @@ func (this *box) OnKeyDown (callback func(key input.Key, numberPad bool)) event.
 func (this *box) OnKeyUp (callback func(key input.Key, numberPad bool)) event.Cookie {
 	return this.on.keyUp.Connect(callback)
 }
+func (this *box) OnStyleChange (callback func()) event.Cookie {
+	return this.on.styleChange.Connect(callback)
+}
+func (this *box) OnIconsChange (callback func()) event.Cookie {
+	return this.on.iconsChange.Connect(callback)
+}
 func (this *box) handleFocusEnter () {
 	this.on.focusEnter.Broadcast()
 }
@@ -441,7 +474,7 @@ func (this *box) doLayout () {
 	// laycnt ++
 	
 	this.innerClippingBounds = this.borderSum().Apply(this.bounds)
-	this.loseCanvas()
+	this.outer.recursiveLoseCanvas()
 }
 
 func (this *box) setParent (parent parent) {
@@ -449,6 +482,7 @@ func (this *box) setParent (parent parent) {
 		this.SetFocused(false)
 	}
 	this.parent = parent
+	this.outer.recursiveReApply()
 }
 
 func (this *box) getParent () parent {
@@ -471,7 +505,7 @@ func (this *box) recursiveRedo () {
 	this.doDraw()
 }
 
-func (this *box) loseCanvas () {
+func (this *box) recursiveLoseCanvas () {
 	this.canvas.InvalidateTo(nil)
 }
 
@@ -496,6 +530,36 @@ func (this *box) invalidateMinimum () {
 	}
 }
 
+func (this *box) recursiveReApply () {
+	if this.getHierarchy() == nil { return }
+	
+	// re-apply styling, icons *if needed*
+
+	// style
+	hierarchyStyleNonce := this.getStyleNonce()
+	if this.lastStyleNonce != hierarchyStyleNonce {
+		// remove old style
+		this.lastStyleNonce = hierarchyStyleNonce
+		if this.styleCookie != nil {
+			this.styleCookie.Close()
+			this.styleCookie = nil
+		}
+
+		// apply new one
+		if style := this.getStyle(); style != nil {
+			this.styleCookie = style.Apply(this.outer)
+		}
+		this.on.styleChange.Broadcast()
+	}
+
+	// icons
+	hierarchyIconsNonce := this.getIconsNonce()
+	if this.lastIconsNonce != hierarchyIconsNonce {
+		this.lastIconsNonce = hierarchyIconsNonce
+		this.on.iconsChange.Broadcast()
+	}
+}
+
 func (this *box) canBeFocused () bool {
 	return this.focusable
 }
@@ -529,7 +593,23 @@ func (this *box) getWindow () tomo.Window {
 	return hierarchy.getWindow()
 }
 
+func (this *box) getStyle () tomo.Style {
+	hierarchy := this.getHierarchy()
+	if hierarchy == nil { return nil }
+	return hierarchy.getStyle()
+}
+
 func (this *box) getHierarchy () *Hierarchy {
 	if this.parent == nil { return nil }
 	return this.parent.getHierarchy()
 }
+
+func (this *box) getStyleNonce () int {
+	// should panic if not in the tree
+	return this.getHierarchy().getStyleNonce()
+}
+
+func (this *box) getIconsNonce () int {
+	// should panic if not in the tree
+	return this.getHierarchy().getIconsNonce()
+}

internal/system/canvasbox.go

@@ -29,7 +29,10 @@ func (this *canvasBox) Invalidate () {
 }
 
 func (this *canvasBox) Draw (can canvas.Canvas) {
+	if can == nil { return }
 	this.box.Draw(can)
-	this.userDrawer.Draw (
-		can.SubCanvas(this.padding.Apply(this.innerClippingBounds)))
+	if this.userDrawer != nil {
+		this.userDrawer.Draw (
+			can.SubCanvas(this.padding.Apply(this.innerClippingBounds)))
+	}
 }

internal/system/containerbox.go

@@ -73,6 +73,24 @@ func (this *containerBox) ScrollTo (point image.Point) {
 	this.invalidateLayout()
 }
 
+func (this *containerBox) RecommendedHeight (width int) int {
+	if this.layout == nil || this.vOverflow {
+		return this.MinimumSize().Y
+	} else {
+		return this.layout.RecommendedHeight(this.layoutHints(), this.children, width) +
+			this.borderAndPaddingSum().Vertical()
+	}
+}
+
+func (this *containerBox) RecommendedWidth (height int) int {
+	if this.layout == nil || this.hOverflow {
+		return this.MinimumSize().X
+	} else {
+		return this.layout.RecommendedWidth(this.layoutHints(), this.children, height) +
+			this.borderAndPaddingSum().Horizontal()
+	}
+}
+
 func (this *containerBox) OnContentBoundsChange (callback func()) event.Cookie {
 	return this.on.contentBoundsChange.Connect(callback)
 }
@@ -335,6 +353,20 @@ func (this *containerBox) recursiveRedo () {
 	}
 }
 
+func (this *containerBox) recursiveLoseCanvas () {
+	this.box.recursiveLoseCanvas()
+	for _, child := range this.children {
+		child.(anyBox).recursiveLoseCanvas()
+	}
+}
+
+func (this *containerBox) recursiveReApply () {
+	this.box.recursiveReApply()
+	for _, child := range this.children {
+		child.(anyBox).recursiveReApply()
+	}
+}
+
 func (this *containerBox) boxUnder (point image.Point, category eventCategory) anyBox {
 	if !point.In(this.bounds) { return nil }
 

internal/system/hierarchy.go

@@ -56,6 +56,7 @@ func (this *System) NewHierarchy (link WindowLink) *Hierarchy {
 		needLayout:  make(util.Set[anyBox]),
 		needDraw:    make(util.Set[anyBox]),
 	}
+	this.hierarchies.Add(hierarchy)
 	return hierarchy
 }
 
@@ -85,7 +86,7 @@ func (this *Hierarchy) Empty () bool {
 // draw to. The Hierarchy will use the canvas.Canvas's bounds to lay itself out.
 func (this *Hierarchy) SetCanvas (can canvas.Canvas) {
 	this.canvas = can
-	if this.root != nil { this.root.loseCanvas() }
+	if this.root != nil { this.root.recursiveLoseCanvas() }
 	this.needRedo = true
 }
 
@@ -135,6 +136,20 @@ func (this *Hierarchy) AfterEvent () {
 	}
 }
 
+// Close closes the Hierarchy. This should be called when the Window that
+// contains it has been closed.
+func (this *Hierarchy) Close () {
+	this.system.removeHierarchy(this)
+}
+
+func (this *Hierarchy) setStyle () {
+	if this.root != nil { this.root.recursiveReApply() }
+}
+
+func (this *Hierarchy) setIcons () {
+	if this.root != nil { this.root.recursiveReApply() }
+}
+
 func (this *Hierarchy) getHierarchy () *Hierarchy {
 	return this
 }
@@ -143,6 +158,18 @@ func (this *Hierarchy) getWindow () tomo.Window {
 	return this.link.GetWindow()
 }
 
+func (this *Hierarchy) getStyle () tomo.Style {
+	return this.system.style
+}
+
+func (this *Hierarchy) getStyleNonce () int {
+	return this.system.styleNonce
+}
+
+func (this *Hierarchy) getIconsNonce () int {
+	return this.system.iconsNonce
+}
+
 func (this *Hierarchy) getCanvas () canvas.Canvas {
 	return this.canvas
 }

internal/system/internal-iface.go

@@ -51,13 +51,17 @@ type anyBox interface {
 
 	// flushActionQueue performs any queued actions, like invalidating the
 	// minimum size or grabbing input focus.
-	flushActionQueue ()
+	flushActionQueue    ()
 	// recursiveRedo recursively recalculates the minimum size, layout, and
 	// re-paints this anyBox and all of its children.
-	recursiveRedo    ()
+	recursiveRedo       ()
 	// loseCanvas causes this anyBox and its children (if applicable) to
 	// lose their canvases and re-cut them as needed.
-	loseCanvas       ()
+	recursiveLoseCanvas ()
+	// recursiveReAppply causes this anyBox and its children (if applicable)
+	// to check whether they have an outdated style or icon set, and if so,
+	// update it and trigger the appropriate event broadcasters.
+	recursiveReApply    ()
 	
 	// contentMinimum returns the minimum dimensions of this box's content
 	contentMinimum   () image.Point
@@ -81,19 +85,19 @@ type anyBox interface {
 	propagate    (func (anyBox) bool) bool
 	propagateAlt (func (anyBox) bool) bool
 
-	handleFocusEnter ()
-	handleFocusLeave ()
-	// handleDndEnter   ()
-	// handleDndLeave   ()
-	// handleDndDrop    (data.Data)
-	handleMouseEnter ()
-	handleMouseLeave ()
-	handleMouseMove  ()
-	handleMouseDown  (input.Button)
-	handleMouseUp    (input.Button)
-	handleScroll     (float64, float64)
-	handleKeyDown    (input.Key, bool)
-	handleKeyUp      (input.Key, bool)
+	handleFocusEnter  ()
+	handleFocusLeave  ()
+	// handleDndEnter    ()
+	// handleDndLeave    ()
+	// handleDndDrop     (data.Data)
+	handleMouseEnter  ()
+	handleMouseLeave  ()
+	handleMouseMove   ()
+	handleMouseDown   (input.Button)
+	handleMouseUp     (input.Button)
+	handleScroll      (float64, float64)
+	handleKeyDown     (input.Key, bool)
+	handleKeyUp       (input.Key, bool)
 }
 
 func assertAnyBox (unknown tomo.Box) anyBox {

internal/system/system.go

@@ -2,12 +2,20 @@ package system
 
 import "io"
 import "image"
+import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/internal/util"
 
 // System is coupled to a tomo.Backend implementation, and manages Hierarchies
 // and Boxes.
 type System struct {
 	link BackendLink
+
+	style      tomo.Style
+	styleNonce int
+	iconsNonce int
+	
+	hierarchies util.Set[*Hierarchy]
 }
 
 // BackendLink allows the System to call up into the tomo.Backend implementation
@@ -15,8 +23,6 @@ type System struct {
 type BackendLink interface {
 	// NewTexture creates a new texture from an image.
 	NewTexture (image.Image) canvas.TextureCloser
-	// NewCanvas creates a new blank canvas with the specified bounds.
-	NewCanvas  (image.Rectangle) canvas.Canvas
 	// NewSurface creates a new surface with the specified bounds.
 	NewSurface (image.Rectangle) (SurfaceLink, error)
 }
@@ -32,6 +38,29 @@ type SurfaceLink interface {
 // New creates a new System.
 func New (link BackendLink) *System {
 	return &System {
-		link: link,
+		link:        link,
+		hierarchies: make(util.Set[*Hierarchy]),
 	}
 }
+
+// SetStyle sets the tomo.Style that is applied to objects, and notifies them
+// that the style has changed.
+func (this *System) SetStyle (style tomo.Style) {
+	this.style = style
+	this.styleNonce ++
+	for hierarchy := range this.hierarchies {
+		hierarchy.setStyle()
+	}
+}
+
+// SetIcons notifies objects that the icons have changed.
+func (this *System) SetIcons (icons tomo.Icons) {
+	this.iconsNonce ++
+	for hierarchy := range this.hierarchies {
+		hierarchy.setIcons()
+	}
+}
+
+func (this *System) removeHierarchy (hierarchy *Hierarchy) {
+	delete(this.hierarchies, hierarchy)
+}

internal/system/textbox.go

@@ -65,6 +65,15 @@ func (this *textBox) ScrollTo (point image.Point) {
 	this.invalidateLayout()
 }
 
+func (this *textBox) RecommendedHeight (width int) int {
+	return this.drawer.ReccomendedHeightFor(width) + this.borderAndPaddingSum().Vertical()
+}
+
+func (this *textBox) RecommendedWidth (height int) int {
+	// TODO maybe not the best idea?
+	return this.MinimumSize().X
+}
+
 func (this *textBox) OnContentBoundsChange (callback func()) event.Cookie {
 	return this.on.contentBoundsChange.Connect(callback)
 }

x/backend.go

@@ -31,10 +31,6 @@ func (this *backendLink) NewTexture (source image.Image) canvas.TextureCloser {
 	return this.backend.NewTexture(source)
 }
 
-func (this *backendLink) NewCanvas (bounds image.Rectangle) canvas.Canvas {
-	return this.backend.NewCanvas(bounds)
-}
-
 func (this *backendLink) NewSurface (bounds image.Rectangle) (system.SurfaceLink, error) {
 	// TODO
 	return nil, errors.New("x: not implemented")
@@ -126,10 +122,18 @@ func (this *Backend) NewTexture (source image.Image) canvas.TextureCloser {
 	return xcanvas.NewTextureFrom(source)
 }
 
-func (this *Backend) NewCanvas (bounds image.Rectangle) canvas.Canvas {
+func (this *Backend) NewCanvas (bounds image.Rectangle) canvas.CanvasCloser {
 	return xcanvas.NewCanvas(this.x, bounds)
 }
 
+func (this *Backend) SetStyle (style tomo.Style) {
+	this.system.SetStyle(style)
+}
+
+func (this *Backend) SetIcons (icons tomo.Icons) {
+	this.system.SetIcons(icons)
+}
+
 func (this *Backend) assert () {
 	if this == nil { panic("x: nil backend") }
 }

x/canvas/canvas.go

@@ -49,9 +49,10 @@ func (this *Canvas) Push (window xproto.Window) {
 }
 
 // Close frees this canvas from the X server.
-func (this *Canvas) Close () {
+func (this *Canvas) Close () error {
 	this.assert()
 	this.Image.Destroy()
+	return nil
 }
 
 func (this *Canvas) assert () {

x/canvas/draw.go

@@ -215,7 +215,7 @@ type fillingContext struct {
 }
 
 func (context *fillingContext) fillPolygonHotOpaque () {
-	for index := 0; index < len(context.boundaries); index += 2 {
+	for index := 0; index < len(context.boundaries) - 1; index += 2 {
 		left  := context.boundaries[index]
 		right := context.boundaries[index + 1]
 
@@ -240,7 +240,7 @@ func (context *fillingContext) fillPolygonHotOpaque () {
 }
 
 func (context *fillingContext) fillPolygonHotTransparent () {
-	for index := 0; index < len(context.boundaries); index += 2 {
+	for index := 0; index < len(context.boundaries) - 1; index += 2 {
 		left  := context.boundaries[index]
 		right := context.boundaries[index + 1]
 

x/event.go

@@ -13,7 +13,7 @@ type scrollSum struct {
 }
 
 // TODO: this needs to be configurable, we need a config api
-const scrollDistance = 16
+const scrollDistance = 32
 
 func (sum *scrollSum) add (button xproto.Button, window *window, state uint16) {
 	if xgbkb.StateToModifiers(state).Shift {

x/window.go

@@ -18,7 +18,6 @@ import "github.com/jezek/xgbutil/keybind"
 import "github.com/jezek/xgbutil/mousebind"
 import "github.com/jezek/xgbutil/xgraphics"
 
-type mainWindow struct { *window }
 type window struct {
 	backend   *Backend
 	hierarchy *system.Hierarchy
@@ -28,10 +27,13 @@ type window struct {
 
 	title string
 
+	leader      *window
 	modalParent *window
 	hasModal    bool
 	shy         bool
 	visible     bool
+	resizeX     bool
+	resizeY     bool
 
 	metrics struct {
 		bounds image.Rectangle
@@ -63,28 +65,24 @@ func (this *windowLink) NotifyMinimumSizeChange () {
 func (this *Backend) NewWindow (
 	bounds image.Rectangle,
 ) (
-	output tomo.MainWindow,
+	output tomo.Window,
 	err error,
 ) {
 	this.assert()
-	window, err := this.newWindow(bounds, false)
-	
-	output = mainWindow { window: window }
-	return output, err
+	return this.newWindow(bounds, false)
 }
 
 func (this *Backend) NewPlainWindow (
 	bounds image.Rectangle,
 ) (
-	output tomo.MainWindow,
+	output tomo.Window,
 	err error,
 ) {
 	this.assert()
 	window, err := this.newWindow(bounds, false)
 	window.setType("dock")
 	
-	output = mainWindow { window: window }
-	return output, err
+	return window, err
 }
 
 func (this *Backend) newWindow (
@@ -100,6 +98,9 @@ func (this *Backend) newWindow (
 	window := &window     { backend: this   }
 	link   := &windowLink { window:  window }
 	window.hierarchy = this.system.NewHierarchy(link)
+	window.leader    = window
+	window.resizeX   = true
+	window.resizeY   = true
 
 	window.xWindow, err = xwindow.Generate(this.x)
 	if err != nil { return }
@@ -178,12 +179,16 @@ func (this *window) SetTitle (title string) {
 	icccm.WmIconNameSet (this.backend.x, this.xWindow.Id, title)
 }
 
-func (this *window) SetIcon (sizes ...image.Image) {
+func (this *window) SetIcon (sizes ...canvas.Texture) {
 	wmIcons := []ewmh.WmIcon { }
-	
+
 	for _, icon := range sizes {
-		width  := icon.Bounds().Max.X
-		height := icon.Bounds().Max.Y
+		icon, ok := icon.(*xcanvas.Texture)
+		if !ok { continue }
+		
+		bounds := icon.Bounds()
+		width  := bounds.Dx()
+		height := bounds.Dy()
 		wmIcon := ewmh.WmIcon {
 			Width:  uint(width),
 			Height: uint(height),
@@ -193,18 +198,14 @@ func (this *window) SetIcon (sizes ...image.Image) {
 		// manually convert image data beacuse of course we have to do
 		// this
 		index := 0
-		for y := 0; y < height; y ++ {
-		for x := 0; x < width;  x ++ {
-			r, g, b, a := icon.At(x, y).RGBA()
-			r >>= 8
-			g >>= 8
-			b >>= 8
-			a >>= 8
+		for y := bounds.Min.Y; y < bounds.Max.Y; y ++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x ++ {
+			pixel := icon.BGRAAt(x, y)
 			wmIcon.Data[index] =
-				(uint(a) << 24) |
-				(uint(r) << 16) |
-				(uint(g) << 8)  |
-				(uint(b) << 0)
+				(uint(pixel.A) << 24) |
+				(uint(pixel.R) << 16) |
+				(uint(pixel.G) << 8)  |
+				(uint(pixel.B) << 0)
 			index ++
 		}}
 		
@@ -217,6 +218,20 @@ func (this *window) SetIcon (sizes ...image.Image) {
 		wmIcons)
 }
 
+func (this *window) SetResizable (x, y bool) {
+	if this.resizeX == x && this.resizeY == y { return }
+	this.resizeX = x
+	this.resizeY = y
+	this.doMinimumSize()
+}
+
+func (this *window) SetBounds (bounds image.Rectangle) {
+	this.xWindow.WMMoveResize (
+		bounds.Min.X, bounds.Min.Y,
+		bounds.Min.X + bounds.Dx(),
+		bounds.Min.Y + bounds.Dy())
+}
+
 func (this *window) NewMenu (bounds image.Rectangle) (tomo.Window, error) {
 	menu, err := this.backend.newWindow (
 		bounds.Add(this.metrics.bounds.Min), true)
@@ -247,19 +262,24 @@ func (this *window) NewModal (bounds image.Rectangle) (tomo.Window, error) {
 	return modal, err
 }
 
-func (this mainWindow) NewChild (bounds image.Rectangle) (tomo.Window, error) {
+func (this *window) NewChild (bounds image.Rectangle) (tomo.Window, error) {
+	leader := this.leader
+	
 	child, err := this.backend.newWindow (
 		bounds.Add(this.metrics.bounds.Min), false)
+	child.leader = leader
 	if err != nil { return nil, err }
-	child.setClientLeader(this.window)
-	this.setClientLeader(this.window)
+	
+	child.setClientLeader(leader)
+	leader.setClientLeader(leader)
+	
 	icccm.WmTransientForSet (
 		this.backend.x,
-		this.xWindow.Id,
-		this.xWindow.Id)
-	this.setType("UTILITY")
-	// this.inheritProperties(this.window)
-	return this, err
+		child.xWindow.Id,
+		leader.xWindow.Id)
+	child.setType("UTILITY")
+	// child.inheritProperties(leader.window)
+	return child, err
 }
 
 func (this *window) Widget () (tomo.Window, error) {
@@ -306,6 +326,7 @@ func (this *window) Close () {
 	this.SetRoot(nil)
 	delete(this.backend.windows, this.xWindow.Id)
 	this.xWindow.Destroy()
+	this.hierarchy.Close()
 }
 
 func (this *window) OnClose (callback func ()) event.Cookie {
@@ -361,7 +382,7 @@ func (this *window) reallocateCanvas () {
 	
 	if larger || smaller {
 		if this.xCanvas != nil {
-			this.xCanvas.Destroy()
+			this.xCanvas.Close()
 		}
 		this.xCanvas = xcanvas.NewCanvasFrom(xgraphics.New (
 			this.backend.x,
@@ -404,14 +425,30 @@ func (this *window) doMinimumSize () {
 	
 	if size.X < 8 { size.X = 8 }
 	if size.Y < 8 { size.Y = 8 }
+
+	hints := icccm.NormalHints {
+		Flags:     icccm.SizeHintPMinSize,
+		MinWidth:  uint(size.X),
+		MinHeight: uint(size.Y),
+		// now you can tell your friends that the max size of a Tomo
+		// window under X when one of the dimensions is constrained is
+		// 99999999999
+		MaxWidth:  uint(99999999999),
+		MaxHeight: uint(99999999999),
+	}
+	if !this.resizeX {
+		hints.Flags   |= icccm.SizeHintPMaxSize
+		hints.MaxWidth = uint(size.X)
+	}
+	if !this.resizeY {
+		hints.Flags    |= icccm.SizeHintPMaxSize
+		hints.MaxHeight = uint(size.Y)
+	}
+	
 	icccm.WmNormalHintsSet (
 		this.backend.x,
 		this.xWindow.Id,
-		&icccm.NormalHints {
-			Flags:     icccm.SizeHintPMinSize,
-			MinWidth:  uint(size.X),
-			MinHeight: uint(size.Y),
-		})
+		&hints)
 	newWidth  := this.metrics.bounds.Dx()
 	newHeight := this.metrics.bounds.Dy()
 	if newWidth  < size.X { newWidth  = size.X }